Method and apparatus for a wide field of view display

ABSTRACT

A method and apparatus for a uniform resolution display screen. In one embodiment, the uniform resolution display screen comprises a surface of the uniform resolution display screen having a curvature configured to display images with a uniform resolution across the display screen. The curvature is based on a projection distance from a projector to the uniform resolution display screen and a viewing distance from an eyepoint of an observer to the uniform resolution display screen. The geometry of the display screen is configured to display images associated with a high definition imaging format.

This Application is a divisional of application Ser. No. 12/028,463,filed Feb. 8, 2008, now issued as U.S. Pat. No. 8,194,193.

BACKGROUND INFORMATION

1. Field

The present disclosure relates generally to display systems. Moreparticularly, the present application is directed to a method andapparatus for a visual image projection and display system that createsa wide field of view display using fixed matrix projectors that arepreferably of high definition format.

2. Background

A simulator is a device that simulates a particular experience asrealistically as possible. For example, a flight simulator simulates theexperience of flying an aircraft, such as an airplane or helicopter. Avehicle driver simulator attempts to create the experience of driving avehicle over streets or off-road terrains. Simulators typically usedisplay systems to create a field of view displaying what the user mightsee if the user were actually flying an aircraft or driving a vehicle.Simulators may also provide simulated controls and steering devicesassociated with the particular aircraft or vehicle, and/or added motionto simulate movement of the aircraft or vehicle.

The visual systems currently in use in simulators were developed for usewith four by three (4:3) aspect ratio cathode ray tube (CRT) projectors.However, currently available simulators do not fully exploit the recentadvances in visual display technology, such as fixed matrix digitalprojectors in general, and especially High Definition Television (HDTV)format fixed matrix projectors with wide aspect ratios, such as, withoutlimitation, sixteen by nine (16:9) aspect ratio format. Also, the modernfixed matrix projectors do not have the ability for image scalingwithout the loss of image resolution since the image source is made upof a mechanically fixed array of image sources instead of a continuousimage surface, as with a CRT projector.

In addition, because the shape of the flat screen segments used totessellate an arrangement of rear projection screens around the eyepointin currently available simulators were designed for four by three (4:3)aspect ratio projectors, the resulting display systems are poorly suitedto the use of wide aspect ratios typically used in high definitionsystems.

For simulation display purposes, the U.S. government has assumed a goalof providing eye-limited visual performance. Existing display systemshave typically used arrangements of flat rear projection screens or domeshaped rear projection screens, neither of which are optimum forcreating an eye-limited wide field of view display with uniformresolution from the eyepoint. In other words, existing display systemscreens are not capable of providing an eye-limited full field of viewdisplay for simulators, such as aircrew training systems.

SUMMARY

An embodiment of the present disclosure provides a uniform resolutiondisplay screen. In one embodiment, the uniform resolution display screencomprises a surface of the uniform resolution display screen having acurvature configured to display images with a uniform resolution acrossthe display screen. The curvature is based on a projection distance froma projector to the uniform resolution display screen and a viewingdistance from an eyepoint of an observer to the uniform resolutiondisplay screen. The geometry of the display screen is configured todisplay images associated with a high definition imaging format.

In another advantageous embodiment, a method of producing a uniformresolution image on a tessellation of spherical surfaces acting asrear-projection screens is provided. A tessellation of a sphere usingspherical surfaces associated with a set of display screens is created.The tessellation of the spherical surfaces surrounds an eyepoint of aviewer on all sides and a top of the tessellation of the sphericalsurfaces. Each screen in the set of display screens has a selectedcurvature. A set of projectors generates images for display on thetessellation of the spherical surfaces associated with the set ofdisplay screens.

In yet another advantageous embodiment, a method is provided forproducing a uniform resolution image from a tessellation of sphericalsurfaces acting as rear-projection screens. A set of side screens isselected. Each screen in the set of side screens has a selectedcurvature. A top screen is selected. The set of side screens and the topscreen forms a tessellated sphere of display screens. A set ofprojectors is selected. Each projector in the set of projectorsgenerates images for display on the tessellated sphere of displayscreens. The set of side screens, the top screen and the set ofprojectors forms a visual image and display system. The visual image anddisplay system generates a full field of view display with a uniformresolution on a surface of the tessellated sphere of display screens.

In still another advantageous embodiment, a visual image projection anddisplay system is provided. The visual image projection and displaysystem comprises a set of screens having a selected curvature. Theselected curvature is determined using a locus of points created by anintersection of lines drawn at equal angular increments from an eyepointwith a set of lines drawn at equal pixel increments at an image sourcethrough a projection point. Images displayed on screens in the set ofscreens having the selected curvature are displayed with uniformresolution. A set of projectors generate images displayed on the set ofscreens to form a full field of view display.

Another advantageous embodiment provides a visual image projection anddisplay system that provides a tessellation of spherical surfaces actingas rear-projection screens. A geometrically normal ray from a point on aconcave side of a first spherical surface in the tessellation ofspherical surfaces intersects with a geometric normal ray from a pointon a concave side of each other spherical surfaces in the tessellationof spherical surfaces at or near an eye position of an observer. A setof projectors is located on a convex side of each spherical surface inthe tessellation of spherical surfaces. Each projector in the set ofprojectors generates an image to form a plurality of images. Theplurality of images is displayed on the tessellation of sphericalsurfaces with uniform resolution.

Thus, the advantageous embodiments provide a method and apparatus forcreating a full field of view display system to overcome the problem ofinefficient utilization of an image generator and display pixels whenpixels are projected by fixed matrix high definition format projectorsrather than analog CRT projectors to form a continuous full field ofview image on a rear projection screen for viewing. The features,functions, and advantages can be achieved independently in variousembodiments of the present disclosure or may be combined in yet otherembodiments in which further details can be seen with reference to thefollowing description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the advantageousembodiments are set forth in the appended claims. The advantageousembodiments, however, as well as a preferred mode of use, furtherobjectives and advantages thereof, will best be understood by referenceto the following detailed description of an advantageous embodiment ofthe present disclosure when read in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is a block diagram of a prior art flight simulator;

FIG. 2 is a block diagram showing an aspect ratio for a standard displayscreen and a high definition display screen;

FIG. 3 is a block diagram illustrating a currently used display screenfor use in a flight simulator based on the geometry of a modifieddodecahedron;

FIG. 4 is a block diagram of a simulator in accordance with anadvantageous embodiment;

FIG. 5 is a block diagram of display screens in accordance with anadvantageous embodiment;

FIG. 6 is a block diagram illustrating a rectangular lower side screenwith three (3) sixteen by nine (16:9) overlays in accordance with anadvantageous embodiment;

FIG. 7 is a block diagram of a hexagonal arrangement of six flatrectangular-trapezoidal side screen pairs in accordance with anadvantageous embodiment;

FIG. 8 is a block diagram of a hexagonal arrangement of sixrectangular-trapezoidal side screen pairs with uniform resolution curvedscreens in accordance with an advantageous embodiment;

FIG. 9 is block diagram of a prior art flat rear-projected screen;

FIG. 10 is a block diagram of a prior art dome shaped rear-projectedscreen;

FIG. 11 is a block diagram of a rear-projection screen with a uniformresolution curvature in accordance with an advantageous embodiment;

FIG. 12 is a graph illustrating a relationship between screen radius andprojection distance in accordance with an advantageous embodiment;

FIG. 13 is a block diagram illustrating a horizontal resolution for aflat screen distance in accordance with an advantageous embodiment;

FIG. 14 is a block diagram illustrating a horizontal resolution for acurved screen distance in accordance with an advantageous embodiment;

FIG. 15 is a block diagram illustrating eyepoint to screen distance inaccordance with an advantageous embodiment;

FIG. 16 is a block diagram of a six-sided display system with fourteenprojectors in accordance with an advantageous embodiment;

FIG. 17 is a block diagram of a six-sided display system with twenty-six(26) projectors in accordance with an advantageous embodiment;

FIG. 18 is a block diagram of a five-sided display system distance inaccordance with an advantageous embodiment;

FIG. 19 is an illustration of a visual image and display system inaccordance with an advantageous embodiment;

FIG. 20 is a flowchart illustrating a process for generating a widefield of view display system in accordance with an advantageousembodiment; and

FIG. 21 is a flowchart illustrating a process for creating a uniformresolution display screen in accordance with an advantageous embodiment.

DETAILED DESCRIPTION

A simulator is a device that simulates a particular experience asrealistically as possible. For example, a flight simulator simulates theexperience of flying an aircraft, such as an airplane or helicopter. Avehicle driver simulator attempts to create the experience of driving avehicle over streets or off-road terrains. Simulators typically usedisplay systems to create a field of view displaying what the user mightsee if the user were actually flying an aircraft or driving a vehicle.The simulator may also provide simulated controls and steering devicesassociated with the particular aircraft or vehicle, and/or added motionto simulate movement of the aircraft or vehicle.

FIG. 1 is a block diagram of a prior art flight simulator. Flightsimulator 100 is a cathode ray tube (CRT) type rear-projection systemflight simulator. Flight simulator 100 includes cathode ray tube (CRT)projectors 102-110. Each of CRT projectors 102-110 produces a light beamcarrying an image. The image is projected onto a mirror, such as mirrors112-120. Each mirror reflects the projected image onto a display screen,such as display screens 122-126.

CRT projectors 102-110 are capable of accommodating aspect ratios, otherthan four by three (4:3) aspect ratios, by rescaling of their horizontaland vertical image sizes. An aspect ratio refers to the relationshipbetween the width and height of a display screen, such as displayscreens 122-126.

Each of display screens 122-126 displays a tessellated image that ispart of a larger view image. In other words, the image on each displayscreen is a piece of a larger image. When the images are displayed ontwo or more of the screens at the same time, the display screens appearto present a single, large image. In this example, the larger image isan image of a view that might be seen through a window in a cockpit.

Flight simulator 100 utilizes a wide field of view rear projectiondisplay screen geometry based on a modified dodecahedron. A dodecahedronuses flat, regular pentagon shapes to tessellate a sphere. However, therear projection display screen geometry based on a modified dodecahedronis not suitable for use with high definition format projectors.

FIG. 2 is a block diagram showing an aspect ratio for a standard displayscreen and a high definition display screen. Display screen 200 is astandard, CRT display screen. The aspect ratio is the ratio of thelonger dimension (width) 202 and the shorter dimension (height) 204 ofthe display screen. In this case, the aspect ration is represented as afour by three (4:3), which is typical of standard CRT televisions.

High definition systems are designed for utilization with higher aspectratios. In other words, high definition systems display images designedfor screens with a greater width. In this example, display screen 210 isa display screen having a width 212 and height 214 relationshiprepresented by a sixteen by nine (16:9) aspect ratio, which is a typicalaspect ratio for high definition technologies. Display screens are notlimited to four by three (4:3) or sixteen by nine (16:9) aspect ratio.Other aspect ratios may also be utilized in display screens.

Recent advances in visual display technology, specifically HighDefinition Television (HDTV) format fixed matrix projectors, have notbeen fully exploited because the visual systems currently in use weredeveloped for use with four by three (4:3) aspect ratio CRT projectors,such as CRT projectors 102-110 in FIG. 1.

FIG. 3 is a block diagram illustrating a currently used display screenfor use in a flight simulator based on the geometry of a modifieddodecahedron. Display screen 300 is an example of a display screen for adisplay system based on the dodecahedron, such as flight simulator 100in FIG. 1. The shape of the flat screen segments used to tessellate anarrangement of rear projection screens around the eyepoint in these CRTprojection systems were designed for four by three (4:3) aspect ratioprojectors. The resulting display systems are poorly suited to use withthe wide aspect format of high definition display systems, such assystems with sixteen by nine (16:9) aspect ratios.

Display screen 300 is a pentagon shaped panel that is not well suited tothe use of fixed matrix high definition format projectors generatingimages with aspect ratios that are greater than four by three (4:3).When high definition projectors that are suited to longer and widerscreens are used with commonly used screen geometries, such as thepentagon screen geometry of display screen 300, the higher aspect ratioimage 302 falls off display screen 300, the image does not fill displayscreen 300 efficiently, and/or the image may appear warped. This resultsin waste and inefficient utilization of pixels to create the image.

Currently, complex screen geometries have evolved to try to optimizevarious display parameters such as resolution, brightness, and variationin eye-relief in CRT projector systems. Especially for wide formatdisplays on flat screens, the pixel density, in terms of angular pixelseparation as viewed by an observer located in a stationary positionnear the center of the screen, is greatest at the perimeter and least inthe center of the display. Conversely, for a rear-projected domedisplay, angular pixel separation as viewed by the same observer locatedat the center of curvature of the screen is least at the center of theimage and greater at its perimeter. Therefore, the advantageousembodiments recognize that currently used screen geometries do notprovide for uniform image resolution.

Considerable investment in system design and fabrication infrastructurehas been made for producing various configurations of these systems byseveral manufacturers. These capabilities have been exploited fully inthe design of the current generation of CRT projection display systemsto help balance out other limitations of CRT projectors, which resultsin a wide range of projector orientations and image aspect ratios.

In addition, existing display systems have typically used arrangementsof flat rear projection screens but have also used spherical shaped rearprojection screens. However, the dome shaped screens do not provideoptimum resolution uniformity and are not well suited for highdefinition format, such as, without limitation, aspect ratios ofapproximately sixteen by nine (16:9).

It will be appreciated by one skilled in the art that the words“optimize”, “optimization,” “optimum,” and related terms are terms ofart that refer to improvements in display resolution, efficiency inpixel utilization, and image quality, and do not purport to indicatethat a display system has achieved, or is capable of achieving, an“optimal” or perfectly uniform resolution, perfect image quality, orflawless image display.

The embodiments recognize that the current flat rear projection screensand the spherical shaped rear projection screens are not optimum forcreating a wide field of view display with uniform resolution from theeyepoint, which is a highly desirable characteristic of a display to beused for training pilots in tactical situations.

Prior art tessellations of images displayed on screens are designed toutilize CRT projectors, which are nominally four by three (4:3) aspectratios with analog adjustment of raster size and aspect. These analogadjustments allow accommodation of a variety of screen shapes withoutloss of image resolution; however, increasingly limited consumer use hasrestricted CRT technology development and increased its cost.

In addition, prior art display systems utilize complex configurations ofscreen types. For example, the M2DART display system uses eight (8)different screen types. The VIDS display system uses seven (7) differentscreen types, including left/right variations. Another prior art displaysystem has only one screen type, but variations in projector orientationresult in different roll orientations for each screen, which is not aserious problem for CRT projectors that can be rolled arbitrarily but isa significant complication for high definition format fixed matrixprojectors which usually cannot be rolled and must use mirrors to rotatethe image on the screen. In addition, the VIDS and M2DART systems havescreens that are all different and there is no symmetry across channelboundaries, which results in poor color and intensity match acrosschannel boundaries.

The advantageous embodiments recognize that existing display systemgeometries are not compatible with the goal of eye-limited visualperformance for aircrew training systems. For simulation displaypurposes, eye-limited visual performance may be considered to beequivalent to an angular sub-tense for two adjacent pixels of twoarc-minutes. This corresponds to 20/20 visual acuity in the Snellen eyechart, which is used to characterize human visual performance. The 20/20visual acuity standard is commonly considered to be “normal” visualperformance when judging the need for corrective lenses and other visioncorrection measures.

Currently available display system technologies cannot currently meetthe goal of providing eye-limited visual performance in simulators.Thus, the advantageous embodiments recognize the need for an affordable,wide field of view display system which is optimized for the current andfuture generation of high definition format projectors by the mostefficient use of projector pixels, which provides an optimum uniformityof resolution, minimum number and complexity of projector installationorientations, and which can be fielded near-term with 20/40 acuity andupgraded in the future to 20/20 by a simple projector replacement.

Recent advances in display microchips are resulting in projectors withmuch higher resolution and reduced support costs, but this newtechnology is most economically available in high definition, wideaspect ratio format. In addition, the trend toward wide format displaysis likely to continue indefinitely due to the high demand for highdefinition and digital cinema systems. Moreover, the display industry isinvesting most current development effort to building high-volumedisplay microchip foundries for fabrication of approximately sixteen bynine (16:9) displays. Any advances in performance or reduction in costwill be of this wide format display type.

Therefore, the advantageous embodiments also recognize the need toreassess the trade-offs, which were made in past designs to live withthe low brightness of CRT projectors in the light of the much greaterbrightness of the new wide format high definition digital projectors.The embodiments also recognize the need for an improved, full field ofview visual system for training the crew of tactical air vehicles thatis capable of using high definition display technologies.

A full field of view display is a display that simulates the full fieldof view as seen by an observer in a simulated environment. For example,a full field of view display for a flight simulator would provide adisplay image that simulates everything a pilot in an aircraft might seewhile inside the cockpit of a particular aircraft. In contrast, a widefield of view display is less than a full field of view. For example, awide field of view may provide images simulating what the pilot inside acockpit would see within a 180 degree range rather than an approximately270 or 360 degree range as might be provided in a full field of viewdisplay. Thus, the advantageous embodiments recognize a need for screengeometries that more closely match high definition image sources andmore efficient utilization of pixels during image generation to createwide field and full field of view displays.

An embodiment of the present disclosure provides a uniform resolutiondisplay screen. In one embodiment, the uniform resolution display screencomprises a surface of the uniform resolution display screen having acurvature configured to display images with a uniform resolution acrossthe display screen. The curvature is based on a projection distance froma projector to the uniform resolution display screen and a viewingdistance from an eyepoint of an observer to the uniform resolutiondisplay screen. The geometry of the display screen is configured todisplay images associated with a high definition imaging format.

In another advantageous embodiment, a method of producing a uniformresolution image from a tessellation of spherical surfaces acting asrear-projection screens is provided. The tessellation of the sphericalsurfaces is not necessarily uniform. In this embodiment, thetessellation of the spherical surfaces is a tessellation of a set ofscreens. Each of the screens has a selected curvature. The tessellationof spherical surfaces surrounds the eyepoint of a viewer on all sidesand top with a set of display screens.

In another embodiment, the tessellation of spherical surfaces comprisesa set of one or more lower side screens having a first selectedcurvature. A set of upper side screens may also are also included. Thescreens in the set of upper side screens have a second selectedcurvature. The set of upper side screens includes one or more upper sidescreens. The lower side screens and upper side screens are partial sidescreens. In other words, a partial side screen does not completely covera side of a simulator. Each screen in the set of lower side screens iscoupled to a corresponding screen in the set of upper side screens tofrom a complete side screen. The complete side screen comprising two ormore partial side screens may be referred to as a side screen pair.Thus, the set of upper side screens and the set of lower side screensforms a set of side screen pairs. A top screen is selected. The set oflower side screens, the set of upper side screens, and the top screenforms a tessellated sphere of display screens.

A set of one or more projectors is selected. Each projector in the setof projectors generates images formatted for high definition. The set ofside screen pairs, the top screen, the set of side screen projectors,and the top screen projector forms a visual image and display system.The visual image and display system generates a full field of viewdisplay with a uniform resolution on a surface of the tessellated sphereof display screens.

In another advantageous embodiment, a method of producing a uniformresolution image on a tessellation of spherical surfaces acting asrear-projection screens is provided. A tessellation of a set of displayscreens forming a sphere of display screens is selected. Thetessellation of the set of display screens surrounds an eyepoint of aviewer on all sides and a top of the sphere. Each screen in the set ofdisplay screens has a selected curvature. A set of projectors isselected. Each projector in the set of projectors generates images fordisplay on the tessellation of the set of display screens. The set ofdisplay screens and the set of projectors form a visual image anddisplay system. The visual image and display system generates a fullfield of view display with a uniform resolution on a surface of thetessellated sphere of display screens.

In yet another advantageous embodiment, a method is provided forproducing a uniform resolution image from a tessellation of sphericalsurfaces acting as rear-projection screens. A set of side screens isselected. Each screen in the set of side screens has a selectedcurvature. A top screen is selected. The set of side screens and the topscreen forms a tessellated sphere of display screens. A set ofprojectors is selected. Each projector in the set of projectorsgenerates images for display on the tessellated sphere of displayscreens. The set of side screens, the top screen and the set ofprojectors forms a visual image and display system. The visual image anddisplay system generates a full field of view display with a uniformresolution on a surface of the tessellated sphere of display screens.

In still another advantageous embodiment, a visual image projection anddisplay system is provided. The visual image projection and displaysystem comprises a set of screens having a selected curvature. Theselected curvature is determined using a locus of points created by anintersection of lines drawn at equal angular increments from an eyepointwith a set of lines drawn at equal pixel increments at an image sourcethrough a projection point. Images displayed on screens in the set ofscreens having the selected curvature are displayed with uniformresolution. A set of projectors generate images displayed on the set ofscreens to form a full field of view display.

Another advantageous embodiment provides a visual image projection anddisplay system that provides a tessellation of spherical surfaces actingas rear-projection screens. A geometrically normal ray from a point on aconcave side of a first spherical surface in the tessellation ofspherical surfaces intersects with a geometric normal ray from a pointon a concave side of each other spherical surfaces in the tessellationof spherical surfaces at or near an eye position of an observer. A setof projectors is located on a convex side of each spherical surface inthe tessellation of spherical surfaces. Each projector in the set ofprojectors generates an image to form a plurality of images. Thepluralities of images are displayed on the tessellation of sphericalsurfaces with uniform resolution.

The uniform resolution produced by the uniform resolution curvature ofthe embodiments is not required to be precisely uniform resolution ofthe image across the screen. Uniform resolution is a term of art thatrefers to improvements in display resolution or substantially uniformresolution and does not purport to indicate that a display system hasachieved, or is capable of achieving, a perfectly uniform resolution,perfect image quality, or flawless image display.

The display system of the advantageous embodiments provides tessellationoptimized for efficient use of high definition aspect ratio displayformats, such as, but not limited to, sixteen by nine (16:9) aspectratio formats. The display system provides 20/40 acuity displayconfigurations and 20/20 acuity display configurations that differ onlyby number of pixels provided by each projector. Thus, embodiments forthe 20/40 display configuration system can be easily upgraded to a 20/20acuity display configuration. In addition, the display system does notrequire projectors to be rolled about their optical axis. The radialsymmetry about vertical axis also allows modularity of screen segments,projector support structure, and image generator hardware. Theembodiments having the more optimum screen curvature enables uniformresolution and minimizes wasted pixels.

In this manner, a wide field of view display system for simulators thatmeets either a near 20/20 acuity requirement for the visual display or a20/40 acuity requirement. Where the system has 20/40 acuity, the displaysystem of the advantageous embodiments can be easily upgraded to providea full field of view display with a 20/20 acuity.

The embodiments in FIGS. 4-21 are described as primarily beingimplemented in display systems having sixteen by nine (16:9) aspectratios or approximately 16:9 aspect ratios. However, the embodiments arenot limited to implementation in systems having 16:9 aspect ratios. Theembodiments may be implemented in any system having fixed matrixprojectors with any aspect ratio without departing from the scope of theembodiments. For example, the embodiments may be implemented usingprojectors for generating images having aspect ratios including, but notlimited to, four by three (4:3), three by two (3:2), and one by one(1:1). The embodiments also encompass display systems having aspectratios of approximately 16:9 in compliance with standards such as,without limitation, the Digital Cinema Initiatives (DCI) standards of4096×2160 pixels and 2048×1080 pixels, as well as the Video ElectronicsStandards Association (VESA) standards which specify 1920×1200 pixelsfor approximately 16:9 aspect ratios.

FIG. 4 is a block diagram of a simulator in accordance with anadvantageous embodiment. Simulator 400 is any type of visual displaysystem for providing a full field of view display, such as, but notlimited to, a flight simulator, a vehicle driver simulator, aplanetarium display system, or any other type of full field of viewdisplay system. In this example, simulator 400 is a flight simulator.

Simulator 400 includes set of side screens 401. Set of side screens 401is a set of one or more display screens. In other words, set of sidescreens 401 may include a single screen or two or more screens. Thescreens in set of side screens 401 may be flat display screens ordisplay screens that are curved to create uniform resolution of the fullview image displayed on the screens.

Set of side screens 401 optionally includes partial side screens, suchas, without limitation, set of lower side screens 402 and set of upperside screens 404. In this example, a single lower side screen and anassociated upper side screen forms a side screen pair. A side screenpair is a side screen that is formed by connecting an upper side screento a lower side screen member. In another embodiment, a side screen is asingle unit or member, rather than a screen comprising an upper portionand a lower portion.

Set of lower side screen 402 includes two or more screens. The screensmay be any shape or size. For example, and without limitation, thescreens may be rectangular, square, trapezoidal, pentagonal, or anyother n-sided polygon geometry shape. The screens may be frontprojection screens or rear projection screens. In this example, set oflower side screens 402 includes, without limitation, rear projectionrectangular screens.

Set of upper side screens 404 includes two or more screens. For example,and without limitation, the screens may be rectangular, square,trapezoidal, pentagonal, or any other shape. The screens may be frontprojection screens or rear projection screens.

In this example, set of upper side screens 404 includes, withoutlimitation, rear projection trapezoidal screens, in which one upper sidescreen is associated with each lower side screen in set of lower sidescreens 402. In other words, each upper side screen has a correspondinglower side screen. Thus, if set of lower side screens 402 includes fivescreens, then set of upper side screens 404 also includes five screens.However, if set of lower side screen includes six screens, then set ofupper side screens also includes six screens.

In this example, simulator 400 includes six rectangular-trapezoidal sidescreens and six trapezoidal upper side screens. However, simulator 400may also have only five rectangular-trapezoidal side screen pairs,rather than six rectangular-trapezoidal side screen pairs. Likewise, theembodiments are not limited to rectangular-trapezoidal side screenpairs. The upper and lower side screens may be any shaped screens fordisplaying images.

Set of projectors 405 is a set of one or more projectors. The projectorsin set of projectors 405 may be homogenous projectors of the same type,the same aspect ratio, and/or the same number of pixels. In anotherembodiment, set of projectors 405 includes heterogeneous projectorshaving different types of projectors, different numbers of pixels,and/or generating images with different aspect ratios.

Set of projectors optionally includes set of side screen projectors 406.Set of side screen projectors 406 is a set of one (2) or more projectorsassociated with each side screen in set of side screens 401. Set of sidescreen projectors 406 may include any number of projectors, including,without limitation, one (1) projector, five (5) projectors, ten (10)projectors, twelve (12) projectors, fifteen (15) projectors, eighteen(18) projectors, twenty-six (26) projectors, or any other number ofprojectors.

In this embodiment, set of side screen projectors 406 includes projectormodules which are identically configured with four (4) projectors foreach rectangular-trapezoidal side screen pair for the hexagonalfootprint configuration of the six-sided simulator configuration. Inthis configuration, three projectors are overlapped and blended on eachlarge rectangular screen in set of rectangular lower side screens 402and a single projector displays an image on each trapezoidal screen inset of trapezoidal upper side screens 404 to form the mountingarrangement of four projectors for each rectangular-trapezoidal screenpair. However, in another embodiment, the two or more projectors areconfigured in a non-overlapping manner such that each side screen has asingle projector and the projectors used on the larger rectangular lowerside screens may be of a different type from the ones used on thetrapezoidal upper side screen.

Thus, set of side screen projectors 406 includes a total of twenty-four(24) projectors, in which four projectors project an overlapping imageonto each rectangular-trapezoidal side screen pair. If simulator 400 hasonly five sides instead of six sides, set of side screen projectors 406in a four (4) projector-modular mounting configuration includes twenty(20) projectors.

In another embodiment, set of side screen projectors 406 includesprojectors in a three (3) projector-mounting configuration for eachrectangular-trapezoidal side screen pair. In this example, where thereare six side screen pairs, set of side screen projectors 406 is a set ofeighteen (18) projectors. Where simulator 400 has only five side screenpairs, set of side screen projectors 406 has fifteen (15) projectors.

In yet another embodiment, set of side screen projectors includes asingle projector for each side screen. In such a case, set of sidescreen projectors 406 may include a single projector if there is only asingle side screen in set of side screens 401, five projectors if set ofside screens 401 includes five side screens, or six projectors if set ofside screens 401 includes six side screens.

Simulator 400 optionally includes top screen 408. Top screen 408 is asingle top screen for displaying images in a high definition format. Topscreen 408 may be a square shape, a pentagonal shape, a hexagonal shape,or any other shaped screen for displaying images. In this example, topscreen 408 is a hexagonal top screen.

Set of projectors 405 optionally includes top screen projector 410. Topscreen projector 410 is one or more projectors in a unique projectorarrangement for top screen 408. For example, top screen projector 410may include, without limitation, a single projector or a pair ofprojectors. In this embodiment, none of the images are rotated on thescreen so additional mirrors may not be required for projector roll. Inother words, the projectors in set of side screen projectors 406 and topscreen projector 410 are oriented with zero roll.

Simulator 400 may optionally include a set of one or more mirrors (notshown). One or more projector images may be rotated into portrait modeusing one or more mirrors. Also, in this embodiment, set of side screens401 includes two types of side screens, upper side screens and lowerside screens. In another embodiment, set of side screens 401 is a singletype of side screen. In other words, all the side screens in set of sidescreens 401 is a single size and shape of side screen. In anotherexample, set of side screens 401 includes three or more types of sidescreens. In this example, set of side screens 401 includes screenshaving two or more sizes of screens and/or two or more shapes ofscreens.

FIG. 5 is a block diagram of display screens in accordance with anadvantageous embodiment. In this embodiment, only three differentdisplay screen types are provided for utilization in a single simulator.

Rectangular screen 502 is a rectangular display screen. In this example,rectangular screen 502 is a rear projection screen, such as, withoutlimitation, a screen in set of rectangular lower side screens 402 inFIG. 4.

Trapezoidal screen 504 is a rear projection high definition formatdisplay screen, such as the screens in set of trapezoidal upper sidescreens 404 in FIG. 4. Trapezoidal screen 504 is arranged directly aboverectangular screen 502 and is tilted toward the eyepoint atapproximately forty-five (45) degrees.

Top screen 506 is a rear projection top screen having a square shape.Top screen 508 is a rear projection screen having a pentagonal shape.Top screen 510 is a hexagonal rear projection top screen. Only a singletop screen is used for a single simulator, such as top screen 408 inFIG. 4. The top screen may be a square top screen, such as top screen506, a pentagonal top screen, such as top screen 508, or a hexagonal topscreen, such as top screen 510. In this example, the top screen is a topscreen with approximately sixteen by nine (16:9) image overlays.

Thus, this embodiment provides display screens and display screen imagetessellations optimized for fixed matrix projectors where a user may notbe able to alter, adjust, or modify the geometry of the image generatedby the projectors, such as, without limitation, high definition aspectratio projectors having approximately sixteen by nine (16:9) aspectratios. In addition, the screen configurations are symmetrical acrossall channel boundaries except for the top screen.

Display screen 502 may be used with a set of two or more screens to forma tessellation of screens. However, the embodiments do not require thedisplay screens to be used in a tessellation of screens. Each displayscreen in display screens 502-510 may be used alone or in combinationwith one or more other screens to display images. In other words,display screen 502 may be used as a single display screen alone todisplay images or display screen 502 may be used in conjunction with oneor more other display screens to display images. Moreover, each displayscreen in display screens 502-510 may be a flat screen or a screenhaving an optimized curvature for displaying images with uniformresolution. Thus, in one embodiment, display screen 502 has an optimizedcurvature and is used alone without any other display screens or inconjunction with one or more additional display screens to displayimages with uniform resolution. The one or more additional displayscreens may optionally be flat screens or screens having an optimizedcurvature for displaying images with uniform resolution.

The display screens in FIG. 5 may be manufactured or created using anyknown or available methods for creating display screens having a flatsurface. The display screens may be manufactured using any type ofmaterial for manufacturing display screens. In another embodiment, thedisplay screens have an optimum curvature to display an image withsubstantially uniform resolution. In this embodiment, the displayscreens may be custom manufactured to produce the curved screens havingthe selected curvature, in addition to, or instead of manufacturingaccording to known methods.

FIG. 6 is a block diagram illustrating a rectangular lower side screenwith three (3) image overlays in accordance with an advantageousembodiment.

Screen 600 may be any type of display screen for displaying an image. Inthis example, screen 600 is a rectangular rear projection screen forhigh definition format images, such as, without limitation, a screen inset of rectangular lower side screens 402 in FIG. 4.

A set of two (2) or more projectors projects an overlapping image onscreen 600 to form the image overlays. In this example, each projectorin a set of three (3) projectors projects an overlapped and blendedimage on screen 600. A first projector projects image 602. A secondprojector projects image 604 onto rectangular screen 600. A thirdprojector projects image 606 onto rectangular screen 600 to form ablended image on rectangular screen 600. Overlap 608 occurs where alower portion of image 602 overlaps with an upper portion of image 604.Overlap 610 occurs where a lower portion of image 604 overlaps with anupper portion of image 606. Blending of the overlapping portions 608 and610 of images 602-606 may be performed using any known or availabletechnique for merging the images from multiple projectors into a singleblended image.

FIG. 7 is a block diagram of a hexagonal arrangement of six flatrectangular-trapezoidal side screen pairs in accordance with anadvantageous embodiment. Simulator 700 is a simulator for producing afull field of view display, such as simulator 400 in FIG. 4.

Rectangular lower side screens 702-706 are rectangular, high definitionformat rear projection screens, such as rectangular screen 502 in FIG.5. Simulator 700 is a hexagonal arrangement of six (6) verticalrectangular-trapezoidal side screen pairs. In this figure, three (3) ofthe side screen pairs are visible and three (3) of the side screen pairsare not visible.

Trapezoidal upper side screens 708-712 are arranged directly above eachlarge rectangular lower side screen. Each of trapezoidal upper sidescreens 708-712 is associated with a corresponding rectangular lowerside screen. In this figure, rectangular lower side screen 702 isarranged directly below trapezoidal upper side screen 708. Rectangularlower side screen 704 and trapezoidal upper side screen 710 forms arectangular-trapezoidal side screen pair. Trapezoidal upper side screen712 is arranged directly above rectangular lower side screen 706 to formanother rectangular-trapezoidal side screen pair.

Top screen 714 is a single, rear projection top screen. Top screen 714may be a square shape, such as top screen 506 in FIG. 5, a pentagonshape, such as top screen 508 in FIG. 5, or a hexagonal shaped topscreen, such as top screen 510 in FIG. 5.

Trapezoidal upper side screens 708-712 are tilted downward toward theeyepoint at approximately forty-five (45) degrees in this example. Therectangular lower side screens are tilted at approximately ninety (90)degrees upward. The rectangular-trapezoidal side screen pairs provide360-degree horizontal full field of view.

The long axis of projectors as mounted for large rectangular lower sidescreens 702-706 and trapezoidal upper side screens 708-712 are allhorizontal so that no projector roll is required and so that all of theprojectors for each large rectangular screen and the trapezoidal screenabove it can be mounted on a common mechanical structure, which isidentical for each of the rectangular-trapezoidal screen pairs.

FIG. 8 is a block diagram of a hexagonal arrangement of six (6)rectangular-trapezoidal side screen pairs with uniform resolution curvedscreens in accordance with an advantageous embodiment. Simulator 800 isa simulator, such as simulator 400 in FIG. 4.

Rectangular lower side screens, such as rectangular screens 802-806 arecurved rather than flat screens. The trapezoidal upper side screens,such as trapezoidal screens 808-812, and top screen 814 are slightlycurved. Simulator 800 generates the same field of view as the flatscreens in simulator 700 in FIG. 7, except that the full field of viewimage has a uniform resolution.

Simulator 820 is a cross section illustrating the optimum uniformitycurved screen generated from flat screens by projecting edges onto aspherical surface of optimum radius based on the eyepoint and projector.Section 830 is a view of curvature 832 in rectangular screen 806 andtrapezoidal screen 812. Curvature 832 in the rectangular-trapezoidalscreen pair produces a uniform resolution in the full field of viewscreen.

FIG. 9 is a block diagram of a prior art flat rear-projected screen.Projection geometry 900 is an illustration of an image projected onto aflat, rear-projection screen. Image origin 902 is an origin of an imagegenerated by a fixed rectangular array of sources associated with a highdefinition format projector, such as an array of pixels. Conventionprojection lens 904 is a lens for focusing and magnifying the imageproduced by the fixed rectangular array of sources. Conventionalprojection lens 904 is typically located inside the projector.

Rays 906 are light rays carrying the image. Rays 906 are projected fromthe image source. In this case, the image source is the projector. Rays906 are separated by a fixed distance “Δh”. Thus, rays 906 are equallyspaced height rays projected onto plane 909, which represents a flatscreen.

Rays 908 are projected with a constant increment of height “Δh” toproduce a higher angular resolution at the edge of the flat screenrepresented by plane 909 than at the center of flat screen 909. Whenequally spaced height rays 906 are projected onto plane 909, unequalangles 908 result when the image is viewed at eyepoint 910. Thus, theresolution of the image displayed on flat screen 909 varies inresolution from the center of the screen to the edges of the screen whenviewed by an observer inside a simulator at approximately the center ofthe simulator at design eyepoint 910 to create a non-uniform imageresolution on the flat screen.

FIG. 10 is a block diagram of a prior art spherical rear-projectedscreen. Projection geometry 1000 is an illustration of an imageprojected onto a spherical, dome shaped, rear-projected screen. A usersitting at the center curvature at the radius of the sphere views theimages displayed on the dome shaped screen.

Image origin 1002 is an origin of an image generated by a fixedrectangular array of sources in a projector, such as an array of pixels.Conventional projection lens 1004 is a lens in the projector that isused to focus and magnify the image generated by the array of sources.Rays 1006 projected from image origin 1002 are separated by a fixeddistance “Δh” when sliced by planes.

Screen 1007 is a spherical, dome-shaped rear projection screen. Rays1006 projected with constant increment of height “Δh” at intersectingplane 1012 produce a lower angular resolution at the edge of screen 1007than at the center of screen 1007 when viewed from design eyepoint 1010.Thus, when rays with equally spaced height 1006 are projected onto aspherical surface, such as screen 1007, with eyepoint 1010 at the centerof curvature, angular rays 1008 from eyepoint 1010 are separated by aconstant angle. Instead, angular ray angles 1008 are close together atthe center of the screen 1007 than at the edges of screen 1007. In otherwords, equal height in rays 1006 result in unequal angle separation inrays 1008 and variable resolutions in the displayed image viewed from1010. This results in inefficient use of pixels and non-optimal imageresolution.

In an advantageous embodiment, a single display screen having anoptimized screen curvature is provided to display images with a uniformresolution. As shown in FIGS. 9 and 10, prior art flat screens and domeshaped screens do not provide uniform resolution. However, a screenhaving an optimized curvature in accordance with the embodiment shown inFIG. 11 enables display of images on the screen with uniform resolution.

The uniform resolution screen curvature is the curvature of a screenthat is necessary to produce uniform resolution of images displayed onthe screen or near uniform resolution. The uniform resolution screencurvature maps equal sized pixels in a projector to equal angles asviewed from the eyepoint in the user's field of view.

FIG. 11 is a block diagram of a rear-projection screen with a uniformresolution curvature in accordance with an advantageous embodiment.Projection geometry 1100 is a diagram of an image projected onto aslightly curved screen to generate an image with uniform resolution.Image origin 1101 is an origin of an image generated by a fixed,rectangular array of sources, such as pixels in fixed matrix formatprojector. Convention projection lens 1102 is implemented as any type ofknown or available projection lens for projecting an image onto a rearprojection screen.

Rays 1104 are projected from image origin 1101 and are separated by afixed distance “Δh”. The equally spaced heights of rays 1104 projectedfrom image origin 1101 and intersect plane 1110. Plane 1110 represents aflat rear projection screen. Curved surface 1112 represents a slightlycurved rear projection screen. Curve 1113 represents the location of atraditional curved projection screen with a constant radial distance todesign eyepoint 1106. Design eyepoint 1106 is the point at which anobserver might observe the image displayed on a flat screen at plane1110, curved screen 1112 or curved screen 1113. Center of curvature 1108is a center of curvature of a rear projection screen producing uniformresolution in conjunction with rear projection from a fixed matrixprojector. The equal angular rays 1114 from eyepoint 1106 areintersected with the equal height rays 1104 to form a locus of pointsdefining the uniform resolution screen curvature at plane 1112.

Thus, as shown in FIG. 11, there is an optimum screen curvature shownfor a screen shown at location 1112 such that equal distances in theformat of the projector's imaging chip are mapped onto equal angles forthe viewing position at design eyepoint 1106. This curve can beapproximated to a high degree of accuracy by an arc of radius largerthan the distance from eyepoint 1106 to curve 1112 and which varies withprojector distance.

In one embodiment, the curvature of the screen that is necessary to formthe uniform resolution screen curvature is determined by projecting rays1104 from image source 1101, through lens 1102 then through plane 1110with constant separation Δh 1115. Consequently, rays 1114 withequal-angular separation Δθe 1116 are projected from design eyepoint1108 towards plane 1110. The locus of points formed by the intersectionof constant separation rays 1104 and equal angle separation rays 1114thereby define the curvature of the uniform resolution screen 1112. Thecurvature of the uniform resolution screen can be approximated by asection of a sphere with an optimum radius determined by selection of aradius which results in an optimum resolution variation from thatproduced with the uniform resolution screen.

The optimum curvature of the uniform resolution screen is a function ofprojector distance and eyepoint distance as shown in FIG. 12.

FIG. 12 is a graph illustrating a relationship between screen radius andprojection distance in accordance with an advantageous embodiment. Graph1200 is a graph mapping the relationship between screen radius 1202 andprojection distance 1204. In this graph, the optimum relationshipbetween screen radius 1202 and projection distance 1204 is expressed asa percentage of observer viewing distance. As shown in line 1206, theoptimum curve in the rear projection screen to produce a uniformresolution in an image displayed on the screen is determined as afunction of eyepoint distance and projection distance.

Thus, to determine the optimum curve for a particular screen, an optimumradius is determined. The optimum radius may be identified using line1206 to determine the optimum relationship between projection distance,viewing distance, and the radius of a sphere. The viewing distance isthe distance from an observer's eye to the display screen.

FIG. 13 is a block diagram illustrating a horizontal resolution for aflat screen distance in accordance with an advantageous embodiment. FIG.13 shows a horizontal resolution for a flat screen associated with aparticular projector used to display a field of view which is 60 degreeswide and 50 degrees up by 45 degrees down as viewed from the design eye,which may be referred to as a lower side screen and is illustratedfurther in FIG. 16 below.

Display resolution 1300 shows a display resolution in arc-minutes peroptical line pair. In optical line pairs, a black line is displayed witha white line. The resolution indicates how many black line and whiteline pairs can be distinguished by a viewer assuming that the projectorprovides a particular number of pixels and that the line pairs displayedhave been pre-filtered to reduce aliasing to an acceptable level suchthat the indicated resolution is discernable for any phasing of the linepairs Vs. the pixel structure of the projectors. At 4096 pixels and 2400projector lines, the horizontal and vertical resolution for a flatscreen having a full field of view display image varies across thescreen.

FIG. 14 is a block diagram illustrating a horizontal and verticalresolution for a curved screen in accordance with an advantageousembodiment but using the same projector, image generator and having thesame field of view from the design eye as for the flat screen shown inFIG. 13 above. Display resolution 1400 shows a display resolution inarc-minutes per optical line pair. At 4096 pixels and 2400 projectorlines, the horizontal and vertical resolution for a slightly curvedscreen having a full field of view display image is nearly uniformacross the screen. In addition, the worst case horizontal and verticalresolutions for the optimally curved screen plotted in FIG. 14 aresignificantly better than the worst case horizontal and verticalresolutions plotted for the flat screen shown in FIG. 13 above.

In this example, a single projector with 4096 by 2400 pixels is used oneach lower side screen. However, in another embodiment, the resolutionof a particular display configuration with a hexagonal arrangement forfighter aircraft applications, such as simulator 1700 in FIG. 17, may bebetter than four (4) arc-minutes per pixel pair with standard 1920 by1080 format high definition projectors which are arranged with three (3)projectors on each lowers side screen. By substituting projectors withat least 3840 by 2160 pixels this same display can be upgraded toprovide two (2) arc-minute resolutions. On a curved screen, such ascurvature 830 in FIG. 8, the resolution is uniform across the screen.

FIG. 15 is a block diagram illustrating eyepoint to screen distance inaccordance with an advantageous embodiment. Eye to screen distances 1500are distances from an observer's eyepoint 1502 to a flat screen 1504 anda curved screen 1506.

The distances from the observer's eyepoint 1502 to the screens are shownfor several critical points. These distances are commonly referred to aseye relief and it is desirable to minimize the variation in thesedistances as encountered by the viewer in order to reduce the change inaccommodation required to focus on the detail found at different pointsin the wide field of view afforded by the display system. As can beseen, the distance from observer's eyepoint 1502 to flat screen 1504 isgreater at each point than the distance from eyepoint to curved screen1506. For example, the distance from eyepoint 1502 to flat screen 1504at point 1508 is 1527 millimeters. However, the distance from observer'seyepoint 1502 to corresponding point 1509 on curved screen 1506 is only1246 millimeters. This is a difference of approximately 281 millimetersin distance from the viewer's eyepoint to the flat screen versus thedistance from the viewer's eyepoint to the corresponding point on thecurved screen.

Another way of representing eye relief that is especially useful forcomparing display and optical systems of different types is by dioptervariation. Diopter is a unit of measurement of the refractive power of alens or curved mirror. A diopter is equal to the reciprocal of the focallength in meters. In this example, a lower diopter variation ispreferred to obtain improved image quality and is especially importantwhen a wide field of view display system is used in a tactical aircrafttraining system in which the pilot is equipped with a helmet mountedcueing system display or night vision goggle display having a fixedfocal length adjusted to the midpoint of the extremes of dioptervariation of the display system. Since it is often necessary for thepilot to view the helmet mounted cueing display or helmet mounted nightvision goggle display at the same time that he is viewing simulatedout-the-window imagery on the wide field of view display system, it isimportant to minimize diopter variation due to the shape and arrangementof the display screens.

Diopter variation 1520 of +/−0.1 diopter is shown for the 6 sidedoptimum curved screen display system 1534 and +/−0.17 diopter for thecomparable flat 6 sided flat screen display 1532. The diopter variationfor two display types 1530 currently in use for pilot training, theM2DART and the VIDS are also shown for comparison purposes. As shown inFIG. 15, the diopter variation is shown to be superior in a six-sidedflat screen simulator 1532, such as simulator 700 in FIG. 7, and insix-sided curved screen simulators 1534, such as simulator 800 in FIG. 8as compared to prior art existing design display types.

Thus, the display screens of the full field of view display systemprovide better resolution uniformity, better worst-case resolution, andlower variation in eye relief by the use of an optimum screen curvature.As a result, this invention is poised to provide the best performancetoday at the lowest cost as well as providing upgrade paths to the bestperformance of the future without having to totally redesign the displaysystem. Existing systems may be able to be marginally upgraded to meetnear term requirements but those existing systems will need to beextensively modified later when upgrading to higher resolution isrequired.

In addition, the resolution of a given display system can be improved byutilizing a projector with a greater number of pixels. In other words,if projectors are being used that provide a 20/40 acuity configuration,a 20/20 acuity configuration can be achieved by replacing the projectorswith the lower number of pixels with projectors having a higher numberof pixels. Thus, this embodiment allows a user to easily upgrade thedisplay system image to full two (2) arc-minute resolution by performinga simple projector exchange.

FIG. 16 is a block diagram of a six-sided display system with fourteenprojectors in accordance with an advantageous embodiment. Simulator 1600is a simulator, such as simulator 400 in FIG. 4.

In this example, simulator 1600 is a six-sided display system populatedwith fourteen high definition type projectors, such as projectors1602-1606. Simulator 1600 produces a four (4) arc-minute resolution.

Simulator 1600 in this example utilizes different types of projectors.Projector 1604 is a smaller, less powerful projector having only 1920 by1200 pixels. For example, projector 1606 is a projector having 4096 by2160 pixels to generate high definition images. Rather than utilizing aset of overlapping projectors to display an image on each side screen,simulator 1600 utilizes a single projector for each side screen. Only asingle projector, such as projector 1606 is used to generate imagescovering the entire side screen, including the upper side screen portionand lower side screen portion of a given side screen. Thus, by using aprojector with a higher number of pixels, only a single projector isused for each side screen rather than two or more overlappingprojectors. Projector 1606 is rotated into portrait mode using mirrors.

Although the simulator in FIG. 16 utilizes mirrors, the display screensand projectors in this embodiment minimizes the need for differentmirrors orientations due to the modularity of the design. In addition,the display system in this example minimizes the complexity of thesupporting structure and lighting enclosure.

FIG. 17 is a block diagram of a six-sided display system with twenty-six(26) projectors in accordance with an advantageous embodiment. Simulator1700 is a simulator, such as simulator 400 in FIG. 4.

In this example, simulator 1700 is a six-sided display system populatedwith twenty-six (26) projectors of currently available high definitiontype, such as projectors 1702-1706. These projectors produce a fullfield of view image with 4.0 arc-minute resolution. When theseprojectors are each replaced with higher resolution projectors which arealso currently available the resolution of the resulting display systemcan be as good as 2.0 arc-minutes.

FIG. 18 is a block diagram of a five-sided display system distance inaccordance with an advantageous embodiment. Simulator 1800 is asimulator, such as simulator 400 in FIG. 4.

In this example, simulator 1800 includes trapezoidal upper side screens1802-1810. Each of trapezoidal upper side screens 1802-1810 isassociated with a corresponding rectangular lower side screen. In thisfigure, rectangular lower side screen 1812 is arranged directly belowtrapezoidal upper side screen 1810.

Rectangular lower side screen 1812 and trapezoidal upper side screen1810 are partial side screens that are connected or coupled together toform a side screen. Two partial side screens coupled together to form aside screen in this example may be referred to herein as arectangular-trapezoidal side screen pair.

In FIG. 18, trapezoidal upper side screen 1808 is arranged directlyabove rectangular lower side screen 1814 to form anotherrectangular-trapezoidal side screen pair. Trapezoidal upper side screen1806 is arranged directly above rectangular lower side screen 1816. Anadditional two rectangular lower side screens associated withtrapezoidal upper side screens 1802 and 1804 are not visible in thisfigure.

Trapezoidal upper side screens 1802-1810 are tilted toward the eyepointat approximately forty-five (45) degrees in this example. The normaldistance from each screen to the eyepoint is nominally one meter. Thelong axis of projectors as mounted for large rectangular lower sidescreens 1812-1816 and trapezoidal upper side screens 1802-1810 are allhorizontal so that no projector roll is required, and so that all of theprojectors for each large rectangular screen and the trapezoidal screenabove it can be mounted on a common mechanical structure, which isidentical for each of the rectangular-trapezoidal screen pairs.

FIG. 19 is an illustration of a visual image and display system inaccordance with an advantageous embodiment. Simulator 1900 is asimulator for displaying wide field of view or full field of viewdisplay images to a user. Simulator may be implemented as a visual anddisplay system, such as simulator 400 in FIG. 4.

Simulator 400 includes side screens 1902-1906. Side screens 1902-1906are single unit, one piece side screens that cover an entire side ofsimulator 1900. In other words, side screen 1902 is a single unit,rather than a side screen that is made of an upper side screen portionand a lower side screen portion connected or associated together to forma side screen.

Side screens 1902-1906 are side screens having a rectangular shape.However, side screens 1902-1906 may be implemented using screens havinga square shape, pentagonal shape, trapezoidal shape, or any other shape.

Simulator 1900 includes a set of projectors, such as projector 1912 and1914. In this example, a single projector projects an image on a singleside screen. For example, projector 1912 projects an image on sidescreen 1902. Simulator 1900 optionally includes a set of mirrors, suchas mirrors 1918 and 1919. In this example, mirror 1918 and 1919 are usedto rotate an image generated by projector 1912 into a portrait mode fordisplay in a correct orientation of the image on side screen 1902 forviewing by a user located inside simulator 1900. Projector 1914 ispositioned above top screen 1910 and configured with a single foldmirror 1916 oriented to direct the image downward onto the top screenwithout necessarily rotating the image.

The display screens and projectors shown in FIGS. 4-19 are only examplesof possible configurations of display screens and projectors. Theadvantageous embodiments are not limited to the configurations ofscreens and projectors shown in FIGS. 4-19. Simulators in accordancewith the advantageous embodiments may include different numbers ofprojectors than the projectors shown in the figures and differentarrangements of the projectors in relation to the display screens.

FIG. 20 is a flowchart illustrating a process for generating a widefield of view display system in accordance with an advantageousembodiment. The process begins when a determination is made as towhether flat screens are to be used (operation 2002). If flat screensare not to be used, uniform resolution screen curvature is identified toproduce a uniform resolution in displayed images across the screen(operation 2004). A uniform resolution screen curvature is identifiedfor each display screen. The optimum radius is identified based oneyepoint and projection distance, as shown in FIG. 12.

After a curvature is identified at operation 2004 or if flat screens arebeing used at step 2002, a set of side screen pairs are selected(operation 2006). After selecting a set of side screen pairs, then, aset of side screen projectors is selected (operation 2008). Adetermination is made as to whether projector image roll is required(operation 2009. If projector image roll is not required, the set ofselected projectors for the side screen pairs is mounted horizontally(operation 2010). If projector image roll is required, each projector ismounted horizontally and mirrors are used to rotate the image (operation2017).

After mounting each side screen projector, a top screen and a top screenprojector is selected (operation 2012) to form the simulator. In otherwords, the completed simulator includes the set of side screen pairs,the top screen, the top screen projector, and the set of projectors forthe side screens.

A determination is made as to whether top screen projector image roll isrequired (operation 2013). If projector image roll is not required, thetop screen projector is mounted horizontally (operation 2018). If imageroll is required (operation 2013) the top screen projector is mountedhorizontally and mirrors used to roll the image (operation 2016).

If projector image roll is required at operation 2013 and has beenrotated by mirrors and the top projector has been mounted horizontally(operation 2018) or if projector image roll is not required and theprojector has been mounted horizontally (operation 2018), the simulatorprojects images generated by the set of side screen projectors and thetop screen projector onto the set of side screens and the top screen toform a full field of view display using fixed-matrix projectors(operation 2014) with the process terminating thereafter.

FIG. 21 is a flowchart illustrating a process for creating a uniformresolution display screen in accordance with an advantageous embodiment.A distance from a design eyepoint to a projection screen is identified(operation 2102). A distance from an image projector, located on theopposite side of the projection screen from the design eyepoint, to theprojection screen is identified (operation 2104). At the point along aline drawn from the design eyepoint to the image projection point andlocated at the identified screen distance, a vertical line is drawn(operation 2106).

A second line is drawn towards and through the vertical line so itintersects the vertical line at an arbitrary distance Δh above the linedrawn in operation 2104. Lines are continued to be drawn from theprojection point above and below a line drawn from the design eyepointto the image projection point so that each intersects the vertical lineat a separation Δh from the previous line. (operation 2108). Next a lineis drawn from the design eyepoint through the vertical line to theprojection point.

A second line is drawn from the design eyepoint so it intersects thevertical line at the same location as the second line drawn in operation2108. The angle between the line drawn between the line drawn to theprojection point and the second line just drawn, defines an angle Δθe.Lines are continued to be drawn originating from design eyepoint aboveand below the first line separated by Δθe (operation 2110). A set ofintersection of lines drawn in operation 2108 with corresponding linesdrawn in operation 2110 is located. The intersection of these linesforms a locus of points defining the curvature of a uniform resolutionscreen (operation 2112) with the process terminating thereafter.

The uniform resolution display screen provides more uniform resolutionthan either prior art flat screens or dome shaped screens. Consequently,it also produces a better worst case resolution for a given field ofview from the viewer eyepoint and a given number of pixels arrangedacross that field of view. This is obvious because in a non uniformresolution display there are variations in resolution such that someparts of the display are better than the average of the resolution atall of the parts of the display whereas on a uniform or nearly uniformresolution display all parts have resolution equal to or very near theaverage resolution. This is important to the design of a visualsimulator for pilot training because the part of the display in whichimportant visual detail will appear in a training scenario cannot bepredicted in advance. Therefore the visual display system must bedesigned so that all parts of the display meet or exceed the worst caseresolution value which has been determined to be required forperformance of the most critical training tasks. The uniform resolutionwide field of view display system described herein can provide thatcritical worst case resolution with fewer pixels and hence at lower costthan any other display system.

An embodiment of the present disclosure provides a visual imageprojection and display system. The visual image projection and displaysystem comprises a tessellation of spherical surfaces acting asrear-projection screens and a plurality of projectors located on aconvex side of each spherical surface in the tessellation of sphericalsurfaces. A geometrically normal ray from a point on a concave side of afirst spherical surface in the tessellation of spherical surfacesintersects with a geometric normal ray from a point on a concave side ofeach other spherical surfaces in the tessellation of spherical surfacesat or near an eye position of an observer. Each projector in theplurality of projectors generates an image having an aspect ratio ofapproximately sixteen by nine (16:9) to form a plurality of images, andwherein the plurality of images is blended on each screen surface toproduce a uniform resolution image.

In another advantageous embodiment, a method of producing a uniformresolution image from a tessellation of spherical surfaces acting asrear-projection screens is provided. A set of lower side screens isselected. The screens in the set of lower side screens have a firstselected curvature. A set of upper side screens is selected. The screensin the set of upper side screens have a second selected curvature. Eachscreen in the set of lower side screens is associated with acorresponding screen in the set of upper side screens to form a sidescreen pair. The set of upper side screens and the set of lower sidescreens form a set of side screen pairs. A top screen is selected. Theset of lower side screens, the set of upper side screens, and the topscreen form a tessellated sphere of display screens. A set of projectorsis selected. Each projector in the set of projectors generates imagesformatted for high definition. The set of side screen pairs, the topscreen, the set of side screen projectors, and the top screen projectorform a visual image and display system. The visual image and displaysystem generate a full field of view display with a uniform resolutionon a surface of the tessellated sphere of display screens.

In yet another advantageous embodiment, a flight simulator is providedthat comprises a set of screens having a selected curvature and a set ofprojectors. The selected curvature is identified based on a relationshipbetween a projection distance from a projector to a given screen in theset of screens and a viewing distance from an eyepoint of an observer tothe given screen, wherein images displayed on screens in the set ofscreens having the selected curvature are displayed with uniformresolution. The set of projectors generate images displayed on the setof screens to form a full field of view display.

The display system of the advantageous embodiments provides an improvedflight simulator. The display system may also be used in vehicle driversimulators, marine simulators, and other simulation devices. The displaysystem may be used for improved training of pilots, drivers, mechanics,flight crew, and other personnel. The display system may also be usedfor design and development of vehicles and aircraft. In addition, thedisplay system may also be used for education, such as in planetariums,as well as in entertainment.

An advantageous embodiment creates an eye-limited 2 arc-minuteresolution or nearly eye-limited 4 arc minute, full field of viewdisplay system depending only upon the choice of projectors used. Itefficiently tiles the full field of view of an air combat trainingvisual display system with modern display high definition aspect ratioprojectors and optimizes resolution uniformity with a minimum of wastedpixels.

The apparatus solves the problem of inefficient utilization of imagegenerator and display pixels when these pixels are projected by fixedmatrix projectors, such as high definition format liquid crystal onsilicon (LCoS) or digital light processing (DLP), rather than analogprojectors, such as cathode ray tube (CRT), to form a continuous fullfield of view image on a rear projection screen for viewing by a pilotin a flight simulator.

The display system is a more efficient use of projector and imagegenerator pixels than is available today from existing solutions. Itdoes this by optimizing screen shape and curvature for high definitionformat projectors. Efficient use of pixels is important because suchpixels are very expensive to procure and to support, and as a result,the visual system may drive the cost of fielding and supporting amission-training center more than any other subsystem. The displaysystem also provides increased modularity, which reduces procurementcosts and support costs. The display systems are also well suited toapplications, which require integration with helmet displays and nightvision goggles.

The flowcharts and block diagrams in the different depicted embodimentsillustrate the architecture, functionality, and operation of somepossible implementations of the apparatus and methods. The function orfunctions noted in the flowchart operations may occur out of the ordernoted in the figures. For example, in some cases, two operations shownin succession may be executed substantially concurrently, or theoperations may sometimes be executed in the reverse order, dependingupon the operation involved.

Input/output or I/O devices can be coupled to the system either directlyor through intervening I/O controllers. These devices may include, forexample, without limitation to keyboards, touch screen displays, andpointing devices. Different communications adapters may also be coupledto the system to enable the data processing system to become coupled toother data processing systems or remote printers or storage devicesthrough intervening private or public networks. Non-limiting examplesare modems and network adapters are just a few of the currentlyavailable types of communications adapters.

The description of the different advantageous embodiments has beenpresented for purposes of illustration and description, and is notintended to be exhaustive or limited to the embodiments in the formdisclosed. Many modifications and variations will be apparent to thoseof ordinary skill in the art. Further, different advantageousembodiments may provide different advantages as compared to otheradvantageous embodiments. The embodiment or embodiments selected arechosen and described in order to best explain the principles of theembodiments, the practical application, and to enable others of ordinaryskill in the art to understand the disclosure for various embodimentswith various modifications as are suited to the particular usecontemplated.

What is claimed is:
 1. A uniform resolution display screen comprising: asurface of the uniform resolution display screen having a curvatureconfigured to display images with a uniform resolution across theuniform resolution display screen, wherein the curvature is based on aprojection distance from a projector to the uniform resolution displayscreen and a viewing distance from an eyepoint of an observer to theuniform resolution display screen, the curvature of the screen isconfigured based on a locus of points created by an intersection oflines drawn at equal angular increments from the eyepoint with a set oflines drawn at equal pixel increments at an image source through theprojection point; and a geometry of the display screen, wherein thegeometry of the display screen is configured to display imagesassociated with a high definition imaging format.
 2. The uniformresolution display screen of claim 1 wherein a worst case resolution ofan image displayed on the uniform resolution display screen with a givenfield of view and a given number of pixels produces the image with abetter resolution than a worst case resolution of the image displayed ona flat display screen or a dome shaped display screen with the givenfield of view and the given number of pixels.
 3. The uniform resolutiondisplay screen of claim 1 wherein the geometry of the uniform resolutiondisplay screen is an n-sided polygon geometry selected from a groupconsisting of a rectangular geometry, a trapezoidal geometry, or apentagonal geometry.
 4. The uniform resolution display screen of claim1, wherein the observer is positioned on a first side of the displayscreen and the projector is positioned on a second side of the displayscreen.
 5. The uniform resolution display screen of claim 1, wherein thedisplay screen displays an image in approximately a sixteen by nineaspect ratio.
 6. A visual display system for use in a simulatorcomprising: a set of screens having a selected curvature, wherein theselected curvature is determined using a locus of points created by anintersection of lines drawn at equal angular increments from an eyepointwith a set of lines drawn at equal pixel increments at an image sourcethrough a projection point, wherein images displayed on screens in theset of screens having the selected curvature are displayed with uniformresolution, the curvature of the screen is configured based on a locusof points created by an intersection of lines drawn at equal angularincrements from the eyepoint with a set of lines drawn at equal pixelincrements at an image source through the projection point; and a set ofprojectors, wherein the set of projectors generate images displayed onthe set of screens to form a full field of view display.
 7. The visualdisplay system of claim 6 wherein the set of screens further comprises:a top screen; and a set of side screens, wherein the set of side screenscomprises partial side screens, and wherein the set of side screens istessellated, wherein a geometrically normal ray from a point on aconcave side of the spherical surface intersects with a geometric normalray from a point on a concave side of each other spherical surface nearan eye position of an observer.
 8. The visual display system of claim 7,wherein each screen in the set of side screens further comprise a set ofpartial side screens comprising a rectangular or trapezoidal shapedscreen.
 9. The visual display system of claim 7, wherein a screen in theset of side screens forms a square, pentagonal, or hexagonalconfiguration.
 10. The visual display system of claim 6 wherein the setof projectors generate images on the set of screens with an aspect ratioof approximately sixteen by nine to form a high definition, full fieldof view display.
 11. The visual display system of claim 6 furthercomprising at least one projector associated with each screen in the setof screens.
 12. The visual display system of claim 6, wherein theobserver is positioned on a first side of a screen in the set of screensand a projector associated with the screen is positioned on a secondside of the screen.
 13. A flight simulator comprising: a number ofscreens; a number of projectors; and the screens in the number ofscreens having a curvature, the curvature defined by a locus of pointsdefined by an intersection of a set of constant separation rays and aset of equiangular separation rays, the set of constant separation raysbeing defined by projecting rays from an image source, through a lens,and through a plane with a constant separation, and the set ofequiangular separation rays defined by projecting rays with equiangularseparation from a design eyepoint towards the plane.
 14. The flightsimulator of claim 13 further comprising an imaging chip, such thatequal distances in the format of the projector's imaging chip are mappedonto equal angles for the viewing position at the eyepoint.
 15. Theflight simulator of claim 13, wherein the number of screens comprises aset of lower side screens and a set of upper side screens.
 16. Theflight simulator or claim 15, wherein the set of lower side screenscomprise curved rectangular screens.
 17. The flight simulator of claim15, wherein the set of upper side screens comprise trapezoidal shapedscreens.
 18. The flight simulator of claim 15 further comprising adisplay configured on the number of screens in approximately a sixteenby nine aspect ratio.